Experimenter

April 2013

Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.

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A sweeping bend will fow better than a ftting, and a 45-degree ftting will fow better than a 90-degree ftting. Where possible, use the confguration that has the best fow. modification. Even with the manufacturer's test information, if you make any deviations to its fuel system design, you will need to do the complete regimen of testing. It is a lot to ask, but your life may depend on it. What a shame it would be to end up destroying the aircraft you worked so long and hard to build, or worse, for lack of a few crucial tests. If your fuel system doesn't perform up to snuff, here are some things you can look at: 1. Make sure all fuel lines and vent lines are free of kinks and dents. Replace them if they are damaged in any way. 2. Eliminate as many turns, bends, fittings, and valves as possible. Less is more in this case. 3. Use sweeping bends in place of angle fittings where you can. 4. Use 45-degree fittings instead of 90-degree fittings if you can. 5. Simplify your fuel system by eliminating extra filters, check valves, shutoff valves, and other fittings wherever it can be done safely. 6. Check all fuel lines for obstructions, especially flexible hoses. This is best done during construction. 7. Fuel flow sensors can restrict fuel flow. Get one that has the least amount of restriction possible. 8. Do not ignore the vent system. Many fuel flow problems can be traced back to improperly designed or installed vent systems. Stick to the manufacturer's plans or copy a system that is proven to be reliable. Be safe at all times. Get plenty of help when positioning your aircraft in a nose-up or nose-down configuration. Use solid supports and chock your wheels. Take your time to be sure everything is safe and solid. Do not run the engine during these tests. It is unnecessary and needlessly dangerous. All flight testing should be done at a safe altitude and location such that you can easily make a safe landing in case of an emergency. We know these tests are cumbersome and frankly a pain in the rear end, but nothing like the pain you will experience if you crack up your new airplane. Engine failures can kill you. If we don't step up and do our part, the FAA will come in and tell us what to do and how to do it. That will make it more difficult to build an airplane and less fun. No one wants that. Do these tests before your first flight and after any fuel system modification, and encourage your friends to do the same. Be safe and promote safety. We like having you around. Dave Prizio has built three airplanes and is working on a fourth. He is a regular contributor to Kitplanes magazine and is a member of the EAA Homebuilt Aircraft Council. EAA Experimenter 49

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